Unsteady-state nonlinear processes accompanying the interaction of an electron beam with an electromagnetic field near the boundary of a transmission band. I. The high-frequency boundary

We present the results of numerical modeling of the transient processes accompanying the interaction of an electron beam with the field of an electrodynamic system near the high-frequency boundary of a transmission band. Depending on its parameters, the system can behave like a reflected-wave tube, a traveling-wave tube, or a resonant oscillator, or else it can combine the properties of these. The parameter ranges corresponding to the regimes of steady-state generation, self-modulation, hard excitation, and hysteresis are indicated. A qualitative explanation is given of the observed phenomena, the nature of which depends to a considerable degree on the deceleration of the electron beam imparting kinetic energy to the field.